A bag with 10 marbles is shown below. (7 gray marbles 2 black marbles and 1 white) A marble is chosen from the bag at random. What are the odds in favor of choosing a grey marble?

The odds are the ratio of the probability of choosing a grey marble to that of not choosing a grey marble.
Probability of choosing a grey marble = 7/10
Probability of not choosing a grey marble = 3/10
Therefore the odds in favor of choosing a grey marble = 7 : 3